I. Field
The present disclosure relates generally to electronics, and more specifically to feedback circuits.
II. Background
A feedback circuit is a circuit in which an output signal is fed back and used to control the operation of the circuit. Feedback circuits are commonly used for various applications such as delta-sigma (ΔΣ) modulators, phase lock loops (PLLs), etc. Different overall functions may be obtained for feedback circuits by using different transfer functions in the forward and feedback paths of the feedback circuits.
A feedback circuit may be implemented with various circuit blocks such as amplifiers, summers, quantizers, etc. Ideally, an amplifier should have zero input offset, so that the output of the amplifier is zero when the input is zero. However, an amplifier typically has some input offset, which would result in the output being non-zero when the input is zero.
In general, the presence of input offsets in circuit blocks of a feedback circuit may lead to direct current (DC) offsets at various points in the feedback circuit. DC offset generally refers to a static value and may be for voltage or current. DC offset may be relatively large at certain points in the feedback circuit. A large DC offset at an output of a circuit block may be undesirable since the DC offset may cut into an output signal range of the circuit block. The circuit block may then have to support the DC offset as well as a desired signal. The DC offset may reduce the signal range of the circuit block and may degrade the performance of the feedback circuit.